1. Field of the Invention
The invention relates to a cooling structure of a cylinder block, and more particularly to a cooling structure of a cylinder block which makes it possible to uniformly cool a bore wall of the cylinder block.
2. Description of the Related Art
A conventional cooling structure of a cylinder block is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2002-30989.
The Japanese Patent Laid-Open Publication No. 2002-30989 discloses a technology in which the temperature of a bore wall is made uniform by providing a water jacket spacer inside a water jacket of a cylinder block of an internal combustion engine. However, the bore wall is overcooled in the vicinity of a coolant hole of a head gasket, and in the vicinity of portions connected to bypass pipes (e.g., an oil cooler, an automatic transmission fluid cooler, and a turbo cooler). This is because a flow speed of coolant in an inner wall of the water jacket becomes high in the vicinity of the coolant hole and in the vicinity of the portions connected to the pipes through which the coolant flows in and flows out of the cylinder block.
Accordingly, in the conventional cooling structure of a cylinder block, it is difficult to uniformly cool the bore wall.